Synthetic rubber-like composition and method of making same



Patented Oct. 10, 1933 SYNTHETIC RUBBER-LIKE COMPOSITION-- AND METHOD OFMAKING SAME Waldo L. Semon, Silver Lake Village, Ohio, as-

signor to The B. F.-Goodrl ch Company, New

York, N. Y., a corporation of New York No Drawing. Continuation oiapplication Serial .No. 320,003, November 16, 1928.

This application September 17, 1932. Serial No. 633,686

18 Claims.

This invention relates to the art of preparing synthetic rubber-likecompositions, and especial- 1y to the art of preparing such compositionsfrom raw materials which themselves are not endowed with the resilienceof rubber. I

Rubber, because of its extraordinarily great resilience, high tensilestrength, and resistance to many of the common corrosive materials, hasfound a very extensive employment in the construction of articles ofmany different kinds. However, natural rubber is comparatively expensive and possesses certain inherent disadvantages. Among the mostimportant of these are its solubility in the common solvents, such asgasoline, benzene, and even vegetable or mineral oils; itsperishability, rubber losing most of its strength and resiliency withina comparatively short time, especially if exposed to direct sunlight;and its sensitiveness to the presence of oxidizing substances, rubberbeing rapidly attacked and destroyed by chlorine, bromine, nitric acid,concentrated sulphuric acid, chromic acid, etc. The synthetic rubbersheretofore prepared have exhibited to an even greater degree the Fabove-named disadvantages of natural rubber without possessing its greatstrength and lively resilience.

The chief object of this invention is to provide resilient compositionsduplicating the more important physical properties of rubber, butwithout its chemical instability. Another object is to provideresilient, rubber-like materials which may readily be manufactured frominexpensive raw materials. Qther objects will appear from the followingdescription of the invention. This invention, in brief, consists indissolving a polymerized vinyl halide, at an elevated temperature, in asubstantially non volatile organic solvent, and allowing the solution tocool, where-,- upon it sets to a stiff rubbery gel.

From the points of view of chemical inertness, cheapness, and ease, ofmanufacture, the poly- -merized vinyl halides are almost ideal rawmateterial.

affected by oxidizing acids, even when hot or concentrated, or byatmospheric oxidation or sunlight. However, these completely polymerizedvinyl halides, because of their horny consistency, their insolubility inthe common volatile solvents such as alcohol, gasoline, acetone, etc.,and their high melting points, are very difficult to form into usefularticles.

Although they are insoluble in practically everything at normaltemperatures, the completely polymerized vinyl halides are soluble in alarge number of solvents at a sufiiciently high temperature. It isaccordingly to be understood that the term insoluble polymerized vinylhalide, or other like terms which are'hereinaftcr employed, refer to anddefine products such as those described, in the preceding paragraph,which are insoluble in all ordinary solvents at room temperatures,although they may be soluble in many such solvents atelevated-temperatures. I5 Thus, if one part by weight of polymerizedvinyl chloride is heated and mixed with two parts ofo-nitro-diphenylether at a temperature of about 180 C. a homogeneoussolution is obtained, which upon cooling to room temperatures, set to are silient rubbery solid of high tensile strength, but with a somewhatlower extensibility than ordi nary soft rubber. It is unaffected bydilute sulfuric or nitric acids or sodium hydroxide solution, or byexposure to the weather.

The insoluble polymerized vinyl halides dissolve at high temperatures ina large number of sol vents, forming rubbery gels when cooled. Forexample, chloronaphthalene, o-nitro di phenylether, dibutyl phthalate,trlcresyl phos= 9d p hate and benzyl benzoate are excellentmlvents I forthe purpose. Such substances as chlorben zene, acetophenone, xylidene,anisole, pyridine, chlorphenol, nitrobenzene or nitrotoluene also formgels with good physical properties, but are too volatile for ordinarypurposes, gradually, evaporating and leaving behind the hard vinylhalide polymer. Certain others such asp-dichlorbenzene, dichloracetone,m-dlnitrobenzene, naphthalene, or nitronaphthalene are good solvents forthe vinyl halides, but are solids at room temperatures, so that the geltends to harden and lose its resiliency. However, mixtures of thesesolid materials with each other, or with non-volatile liquid solventssuch as those first mentioned above, may be liquid at room temperatures,and therefore-be more useful than'the pure solid ma- In general aromatichydrocarbons, chlorinated or nitrated aromatic hydrocarbons, aromaticethers, ketcnes, or esters, aromatic amines,

ethers, or ketones, or esters of inorganic acids,

which are sufficiently non-volatile, among others, have been found to beeffective solvents for the purpose of this invention. However, the fattyoils and fatty acids as well as mineral oils or waxes do not appreciablydissolve the polymerized vinyl halides, even at fairly hightemperatures. The particular type or types of compounds selected assolvents for the polymerized vinyl halide must depend on the cost of thevarious materials and on the chemical properties desired in the finishedproduct.

It is evident that the properties of the rubbery gel which is obtainedby dissolving the insoluble' polymerized vinyl halide at an-elevatedtemperature in an appropriate solvent and then cooling the product, maybe varied between wide limits by varying the proportions of the polymerand the solvent or by selecting a solvent or mixture of solvents of thedesired characteristics. An increased proportion of solvent in generalgives a softer, more resilient, and more extensible product, whereas adecrease in the proportions of solvent gives a harder product of greaterstrength.

A product which is. generally satisfactory where a material resistant toacids is desired is made by dissolving one part by weight of insolublepolymerized vinyl chloride at a temperature of about 180 C. in from oneto four parts of a solvent made by mixing two partso-nitro-diphenylether, one part m-dinitrobenzene, and one partdinitrotoluene. This product is practically unaffected by exposure tooxidizing agents, or to direct sunlight, and is quite permanent, notdeteriorating noticeably with age. Another composition with highresistance to gasoline contains 8 parts of insoluble polymerized vinylchloride, 8 parts of tricresyl phosphate and 3 parts of dibutylphthalate. In general, elastic, rubber-like products are obtained byusing from one-half to four parts of the solvent to one part of theinsoluble polymerized vinyl halide, although the invention is notnecessarily confined to these precise proportions. However, higherproportions of solvent give very soft and weak products, whereas lowerproportions produce tough and horny products.

The product may readily be molded, extruded or otherwise formed to anydesired shape by heating to a sufficiently high temperature. Twosurfaces of the product may be caused to adhere one to the other byheating the surfaces to a temperature approaching that required tolique'sfy the composition, and then bringing them into contact. Fabricsmay be impregnated or coated by.

spreading the composition over their surface while in a heated, liquidcondition, especially if the composition is softened by the addition ofa volatile solvent such as xylene or chlurtoluene or even alpha ethylalpha hexenaldehyde. However, other methods of manufacture may beemployed if desired, the above being merely stated to illustrate thevariety of means which may be employed in fabricating useful articlesfrom the products of this invention.

. If it is desired, pigments, or fillers, or other plastics compatiblewith the aforementioned products may be incorporated therewith, tocheapen the final material, or to lend it special properties, or for anyother purpose.

Rubber-like compositions prepared in the manner hereinabove describedare especially valuable in manufacturing articles or products which arenormally exposed to severe oxidation or to the elements, conditionswhich cause. a rapid deterioration of ordinary soft rubber. For example,fabric impregnated with such compositions, when manufactured intoraincoats, or used for covering automobile tops, will remain serviceableand water-tight for many times the life of similar rubberized fabric.

. Or, when a non-toxic solvent or mixture of solvents is employed inpreparing the composition, it can be used in the manufacture ofgas-masks which will not deteriorate during the storage period.Water-proof boots or shoes of this material will not crack or check, butwill remain flexible and water-tight until they are worn out.

The compositions of this invention are excellent insulators, of highdielectric strength, and are therefore very useful in insulatingelectric wire. The insulating coatings may be applied in the customarymanner by extrusion around the wire. They possess the great advantagesover rubber that the insulation is permanently tough and ,f'exible anddoes not require vulcanization. Since they contain no sulphur and do notcorrode the copper wire, the tinning of the wire may be omitted. Theyare extraordinarily rwistant to ozone and may therefore be used even onhigh tension wires.

Such compositions may be employed as a resilient, noiseless flooring orpaving material, exhibiting a most remarkable resistance to wear orabrasion, especially when properly stiffened by the addition of finepigments. Such flooring compositions have a very long life, and are notdamaged by the accidental spillage of oils as are rubber floors.

Since they are practically unaffected by gasoline, the polymerized vinylchloride gels containing properly selected solvents, when employed inlining gasoline hose, have a very long life, and do not contaminate thegasoline with dissolved substances, orflakes of the lining material.They are of especial value in coating or lining equipment or containerswhich come in contact with strongly corrosive materials such as theoxidizing acids, for which purpose no satisfactorily tough, non-fragile,corrosion resistant material has heretofore been developed.

In short, the compositions of this invention are almost universallyapplicable where a permanent, resilient material is desired.

It is to be understood that the term, halides is employed in theappended claims in. a generic sense to include chlorides, bromides, andiodides, but to exclude fluorides, a sense in which the term isconmionly used.

This application is a continuation of my copending application SerialNo. 326,003, filed November 16, 1928.

While I-have herein disclosed with considerable particularity certainpreferred manners of performing my invention, I do not thereby desire orintend to limit myself solely thereto, for, as hitherto stated, theprecise proportions of the materials utilized may be varied and othermaterialshaving equivalent chemical properties may be employed ifdesired without departing from the spirit and scope of the invention asdefined in the appended claims.

I claim:

1. The method of manufacturing a resilient rubber-like composition,which comprises dissolving an insoluble polymerized vinyl halide at anelevated temperature in a composition which will dissolve thepolymerized vinyl halide only at temperatures considerably above roomtemperature, in such proportions as to form a stiif, resilient positionto gel by cooling it.

3. The method of manufacturing a resilient rubber-like composition,which comprises dissolving insoluble polymerized vinyl chloride at anelevated temperature in a substantially non-volatile composition whichwill-dissolve the polymerized vinyl-halide only at temperaturesconsider-'- ably above room temperature, in the proportions of one partof the polymer and one-half to four parts of the solvent, and causingthe composition to gel by cooling it.

4. The method of manufacturing a resilient rubber-like composition,which comprises dissolving insoluble polymerized vinyl chloride at anelevated temperature in a substantially non-volatile, neutral, liquidcomposition which will dissolve the polymerized vinyl halide only attemperatures considerably above room temperature, in the proportions ofone part of the polymer and onehalf to four parts of the solvent, andcausing the composition to gel by cooling it.

5. The method of manufacturing a resilient rubber-like composition,which comprises dissolving one part of insoluble polymerized vinylchloride at an elevated temperature in from onehalf to four parts of asubstantially non-volatile liquid composition consistinglargely ofaromatic substances, which composition will dissolve the polymerized.vinyl chloride only at temperatures considerably above roomtemperature, and causing the composition to gel by cooling it.

6. The method of manufacturing a resilient rubber-like composition,which comprises dissolving one part of insoluble polymerized vinylchloride at an elevated temperature in from onehalf to four parts of asubstantially non-volatile liquid aromatic composition comprising nitrocompounds, which composition will dissolve the polymerized vinylchloride only at temperatures considerably above room temperature, andcausing the composition to gel by cooling it.

7. The method of manufacturing a resilient rubber-like composition,which comprises dissolving one part of insoluble polymerized vinylchloride at an elevated temperature in from onehalf to four parts of asubstantially non-volatile liquid solvent comprising nitro derivativesof aromatic hydrocarbons, and causing the composition to gel by coolingit.-

8. The method 01 manufacturing a resilient rubber-like composition,which comprises dissolving one part of insoluble polymerized vinylchloride at an elevated temperature in from onehalf to four parts of asubstantially non-volatile liquid composition which will dissolve thepolymerized vinyl chloride only at temperatures considerably above roomtemperature, the said composition comprising o-nitro-diphenylether, andcausing the composition to gel by cooling it.

9. The method of manufacturing a resilient rubber-like composition,which comprises dissolving one part of insoluble polymerized vinylchloride at an elevated temperature in from onehalf to four parts of asolvent containing o-m'trodiphenylether two parts, dinitrobenzene onepart,

and dinitrotoluene one part, and causing the composition to gel bycooling it.

10. A rubber-like resilient composition pared by the method defined inclaim 1.

11. A rubber-like resilient composition pared by the method defined inclaim 2.

12. A rubber-like resilient composition pared by the method defined inclaim 3.

13. A rubber-like resilient composition pared by the method defined inclaim 4.

14. A rubber-like resilient composition pared by the'method defined inclaim 5.

- 15. A rubber-like resilient composition pared by the method defined inclaim 6.

16. A rubber-like resilient composition pared by the method defined inclaim 7.

17. A rubber-like resilient composition pared by the method defined inclaim 8.

18. A rubber-like resilient composition pared by the method defined inclaim 9.

- WALDO L. SEMQN.

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